Linear compressor

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Solution Overview

Problem

Linear compressors face issues with piston misalignment leading to contact with the cylinder, causing abrasion and potential damage due to mechanical losses from rotational motion conversion, and existing solutions like flexible rods fail to prevent fatigue-induced loss of flexibility.

Innovation Solution

A compressor design featuring a piston structure with a guide member and mount member connected to a magnet frame, allowing for axial reciprocation and rotational movement, utilizing a rotational coupling member and stepped portions to prevent forward and backward movement, and employing a gas bearing for lubrication to minimize contact pressure and maintain alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a piston is directly coupled to a magnet frame, then the structure is simple, but the piston reciprocates in an eccentric or inclined state causing contact with the cylinder and abrasion

Engineering Contradiction:
Improvestructure simplicityVSAvoidpiston alignment
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The piston structure is designed to be dynamically adjustable through rotation. The piston body can rotate relative to the magnet frame around a central axis, allowing the piston to dynamically adapt its position and orientation during reciprocating motion. This rotational degree of freedom enables the piston to correct eccentricity and inclination automatically, maintaining proper alignment with the cylinder while keeping the overall structure relatively simple.

Inventive Principle:
Principle #15Dynamics

2Reliability

If a flexible rod is inserted into the piston, then piston misalignment is corrected, but the flexible rod loses its flexible function due to fatigue failure

Engineering Contradiction:
Improvepiston alignmentVSAvoidflexible rod service life
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The connection between the piston and magnet frame is segmented into multiple independent components: the magnet frame, the piston body, and the piston rod. These segments are connected through a rotational joint that allows relative movement. This segmentation eliminates the need for a single long flexible rod that would be subject to fatigue, while still providing the necessary alignment correction through the rotational degree of freedom between segments.

Inventive Principle:
Principle #1Segmentation

3Productivity

If the piston reciprocates at high speed, then compression efficiency is improved, but moment acts on the piston by lubricating refrigerant force causing contact with the cylinder

Engineering Contradiction:
Improvecompression speedVSAvoidpiston stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The piston structure incorporates a feedback mechanism where the piston's rotational position automatically adjusts in response to the distribution of lubricating refrigerant pressure. When the piston experiences eccentric loading or moment forces during high-speed reciprocation, the refrigerant pressure distribution creates a restoring moment that rotates the piston back to the correct alignment. This automatic feedback control maintains piston stability without requiring additional active control systems.

Inventive Principle:
Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design effectively prevents piston contact with the cylinder by allowing self-alignment through lubricant pressure, reducing mechanical stress and enhancing durability by minimizing contact pressure and maintaining alignment, thus reducing wear and tear.

Implementation Method 1

employing a gas bearing for lubrication to minimize contact pressure and maintain alignment

Methodology Applied
Scientific EffectGas bearing: Air Lubrication

Implementation Method 2

employing a gas bearing for lubrication to minimize contact pressure and maintain alignment

Methodology Applied
Scientific EffectLubrication: Lubrication

Implementation Method 3

allowing self-alignment through lubricant pressure

Methodology Applied
Scientific EffectPressure: Pressure Increase

Data Source

PatentEP3812585B1Linear compressor
Publication Date: 2023.04.19 LG ELECTRONICS INC
  • EP3812585B1 patent drawingFigure 1
  • EP3812585B1 patent drawingFigure 2
  • EP3812585B1 patent drawingFigure 3~4(b)

AI summary

Provided is a compressor. Provided is a compressor. The compressor includes a piston structure, which comprises a guide member configured to reciprocate inside a cylinder in an axial direction, and a magnet frame configured to support a mover that moves together with the piston structure. The piston structure includes the guide member and a mount member connected to the magnet frame, and the guide member is coupled to be relatively rotatable with respect to the mount member.